The claim is God is immutable (changeless). Being a first cause requires action or motion of some kind to set off the Big Bang eventually resulting in me typing this right now 13.8 billion years later. I consulted with Google Gemini, and it said I have a valid criticism against the Kalam.
A changeless being must undergo some change to issue a first cause, which means it isn't changeless. It's quite a simple refutation, really.
The only way out is to say, "God is so awesome He can make a change to create the first cause without changing Himself. He is the Changeless Change and the Uncaused Cause."
To that I add, "He is the Is that Isn't."